I have a Marble Molly that was getting huge in my main aquarium. It took a while but I finally caught her and moved her to the nursery. A few days passed and she started dropping babies. That appeared to continue for days. I've never seen so many in my 50+ years of having tropical fish. I soon had dozens in the nursery. I started scooping them out with a cup and moving the fry to my shrimp tank. Now I have dozens in that tank and it doesn't look like I even dented the number in the nursery. How many fry can a very big Molly give birth to?